package com.demo.example.binarytree;

import java.util.Stack;

class Node{
    public int val;
    public Node left;
    public Node right;
    public Node(int val){
        this.val=val;
    }
}
public class PreOrder {
    public static void preOrder(Node root){
        Stack<Node> stack=new Stack<>();
        if(root==null){
            return;
        }
    }
}
